By Rob Krider
Most of us gearheads experienced our first competitive car race in the pinewood derby. A seven inch long piece of wood, four nails, four plastic wheels and a sloped track – that’s it. Gravity is the only motor in this race. At first glance it seems like there isn’t much to the pinewood derby. However, after getting your rear kicked your first year you realize that a pinewood derby car can be as complicated as any real race car. Aerodynamics, rolling friction, center of mass, weight, alignment, lane choice, there are all sorts of things that can make the car roll down the track or get stuck halfway down the hill. Of course, as a seven year old kid you have no idea how to change the center mass of a pinewood derby car, that’s where dad comes along.
An official Boy Scouts of America Pinewood Derby kit is about five bucks. This is the first and last time for the rest of your life, that racing will only cost you five bucks. A can of spray paint and some stickers may rack up a few more coins at the local hobby shop, but all in all you can build one of these racers for less than it costs to go to McDonalds and try to stop your heart.
The Boy Scouts of America started this craze in Manhattan Beach, CA back in 1953 and still hold the reigns on it. Other groups like Awana also run pinewood derby events. It’s a cool thing for the kids and easy for clubs to set up. All you need is a sloped track for the cars to roll down. Some tracks are more high tech and have computer timing and scoring.
Because you aren’t actually driving these cars at high speeds, obviously there isn’t much adrenaline rush in pinewood derby racing. But, as the cars roll down the wooden track there is a bit of a high while you’re waiting to see if your car comes in first. In fact, most people aren’t breathing as the cars are in motion. If you win, you are loving life, if you lose, you want to go home and kick the dog.
If the pinewood derby car is built tough it can last the entire event. Most cars lose a wheel or two during the day (easily fixed by pushing the nail and wheel back into the chassis). The hardest part on the cars isn’t the racing, it’s the thirty or forty eight year old kids grabbing, drooling on, and dropping the car over and over again between rounds of racing (ruining the perfect alignment you worked so hard on).
After a solid week of making sawdust in the garage and trying to turn a wooden block into something that resembles a car you head out to the pinewood derby race. The cars are weighed in (you can make minor adjustments here) and inspected to make sure they are using only Boy Scout supplied components (no cheater axles or tricked out wheels). Then the cars go to impound. The cars are put onto the track and raced three at a time (depending on the width of the track, I’ve seen some ten lanes wide). The race consists of a lever being pulled and the cars all being released to roll down the track. First one to the finish line is the winner. Think of it as drag racing a two by four. The racing is an elimination format and during the event, the winners keep advancing while the losers head back to the trailer (or the tool box, in this case). Finally it will come down to two cars. They will race in a double elimination format (swapping lanes so there is no track advantage). The final car is crowned the champion.
Racers are comprised of Cub Scouts. These are good old fashioned honest young kids working hard for an achievement patch. If you want to compete you’ll need to be a kid between the ages of 5 and 12 years old. So, either invent a time machine and go back to race, or do what I did, get married and get yourself a son. Then you’ll have to sit around impatiently until the kid is old enough to become a Cub Scout. Once he finally hits that magical age, get yourself a drill press, a Dremel, some sand paper and get to work. I mean, get to work, uh, letting your son build the car.
There is glory in the pinewood derby. Winners earn great looking trophies and move on to District Championships. At the Championships the kids get the chance to race against the best of the best. No, they don’t have Girl Scouts as trophy girls.
OH, YOU WANT TO WIN, DO YA?
Just like in real racing, who your daddy is, can make all the difference in your on track success (just ask Dale Jr.) If your dad was a carpenter or a racecar driver, chances are you won your first pinewood derby. For the rest of you (who got your rears kicked by the kid whose dad was a racecar driving carpenter) here is how you win the pinewood derby. Weight is your friend. You want that car to weigh in at 5.0 ounces exactly (we bring our cars to the event heavy and then use a small drill bit to take out weight from the front end until the scale tips 5.04 ounces on the money – which rounds down to 5.0 ounces on the scale readout). Tungsten is a very dense metal and is great for placing weight in the car (use epoxy – anything else will let the weight fall out during the races). The center mass of the car should be as far back as possible to give the car a little extra boost of potential energy converted to kinetic energy as the car transitions from the slope of the track to the flat (Don’t believe me? Go read a physics book).
The wheels need to be as round as possible which can be done by spinning the wheel on a drill press and using some fine sandpaper. The nails, which are the axles, have small burs on them that actually slow the wheels down. The nails need to filed down to a perfect roundness and polished to a mirror image (this is allowed in the rules). A longer wheelbase makes the car more stable on the track. The wheels and axles should be aligned perfectly as they are placed in the car (use a tiny bit of super glue to set the axles and keep them from sliding out of the chassis). Rolling friction is not your friend so having one wheel off of the track (aligned higher in the chassis so the wheel doesn’t touch the ground) will cut your rolling resistance by 25%. Aerodynamics don’t play an enormous role in pinewood derby but building a car that looks like a sailboat with a huge sail on the roof isn’t helping matters. My son’s car had six coats of paint on it and was wet sanded between coats just for a little extra aerodynamic advantage.
If you really want to win, build a scale practice track and then construct ten cars (I’m serious). Race all of them against each other
and the winner goes to the show. Every racer knows that testing and tuning is what really wins championships.
RACER BOY GAUGE
Let’s review the Racer Boy gauge cluster here:
FUEL (Cost): The fuel gauge is near full because this is the cheapest racing on the planet.
RPMs (Adrenaline): The tachometer is at 800 RPMs because watching a piece of wood roll down a wooden track doesn’t really compare to sliding a car sideways at an autocross. However, you can get your adrenaline up by winning some races.
MPH (Danger): The speedometer is at 5 miles per hour because nobody has ever been killed racing a pinewood derby car. However, building the car, you can lose a finger messing around with the drill press.
VOLTS (Time): The volts gauge is over three quarters because this doesn’t take much time to race but you can spend over a week sanding and painting your little wooden car. Then again I’ve seen some kids and dads build the kit during tech inspection at the event (no, they didn’t win).
MILEAGE (Car Wear): The mileage is at just over one tenth of a mile because the track is only about forty feet long. As your car continues to win rounds, you’ll keep racing.
Kids can learn a lot about actual racing from participating in the pinewood derby. They can learn how preparation and a sorted car can bring home victory. They can also learn how nutty their dad is when he starts to go all Penske on the car and tries to build it for him. The important thing is to let the kids build the cars (or at least let them think they built them, anyway). See you at the track.
Originally published December 6th, 2009 on speedsportlife.com
Used by permission
From Pinewood Derby Times Volume 9, Issue 14
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